As thiolcarbamate herbicides, commercial products are available such as those known by common names Thiobencarb, Orbencarb, Esprocarb, Molinate, EPTC, and the like, and they are very useful for controlling gramineous weeds which are strongly hazardous weeds. In addition, it has been known that a complex formulation, comprising a thiolcarbamate herbicide and an active ingredient for controlling broadleaf weeds, galingale weeds or the like, is a labor saving herbicide which exhibits a wide spectrum for controlling weeds.
These formulations including thiolcarbamate herbicides are used mainly in the form of granules for direct application and in the form of emulsifiable concentrates to be diluted for use.
Conventional emulsifiable concentrates are prepared usually by employing an organic solvent and a surfactant with an active ingredient. In general, a herbicidally active ingredient of thiolcarbamate type has a low melting point and most of the herbicidally active ingredients are liquid at common temperature. In addition, another herbicidally active ingredient to be mixed with that of thiolcarbamate type may be equivalent to various ingredients such as a liquid ingredient being compatible with that of thiolcarbamate type and a solid ingredient being slightly soluble therein. In the case where said another ingredient is slightly soluble in the herbicidally active ingredient of thiolcarbamate type, an organic solvent has to be blended thereinto. However, use of an organic solvent brings about various problems including a safety problem to the users of the agricultural chemical because of the phytotoxicity of the organic solvent, a storage problem due to the inflammability of the organic solvent, an environmental pollution problem by its application, a phytotoxicity to crop plants, and the like. Furthermore, in order to emulsify and disperse not only the active ingredient but also the organic solvent used, a surfactant is employed in a large amount, whereby there will be an economical problem as well as a problem of environmental pollution due to the surfactant.
Therefore, for an emulsifiable concentrate, it is desired to essentially solve the above-mentioned various problems attributable to the organic solvent and the surfactant.
A wettable powder and a flowable formulation are conceivable as the types of formulation which may be substituted for the emulsifiable concentrate. However, the wettable powder has a problem of dusting at the time of dilution, and there is a possible danger to the safety of the users. Besides, in the case of a liquid activate ingredient, it is difficult to obtain a highly concentrated formulation as compared with the emulsifiable concentrate. A granulated wettable powder has also been proposed to prevent dusting at the time of dilution, but in the case where the active ingredient is liquid, such a method still has a drawback, that it is difficult to obtain a formulation having a high concentration. On the other hand, a flowable formulation, prepared by having a solid active ingredient suspended and dispersed in water or having a liquid active ingredient emulsified and dispersed in water, usually contains an organic solvent such as ethylene glycol, propylene glycol, or the like in order to impart freeze resistance. Accordingly, it has a problem attributable to such an organic solvent. In addition, it has a problem that the freeze resistance is inadequate in an extremely cold area of -20.degree. C. or lower, whereby it freezes, and when returned to common temperature, the dispersion system will be destroyed, and separation or precipitation will result. Furthermore, in many cases, a flowable formulation is adjusted to have a high viscosity to improve the storage stability at common temperature, whereby the handling at the time of use often tends to be difficult.
As a conventional art to obtain an emulsifiable concentrate without using an organic solvent, there is a non-solvent type of a highly concentrated emulsifiable concentrate (Japanese Patent Application Second Publication No. 53-45370) or an emulsifying agent for an emulsifiable concentrate of an agricultural chemical without using an organic solvent (Japanese Patent Application Second Publication No. 63-39561). By using the art, an emulsifiable concentrate comprising a herbicidally active ingredient of thiolcarbamate type and another herbicidally active ingredient which can be dissolved in the herbicidally active ingredient of thiolcarbamate type may be obtained. However, when said another herbicidally active ingredient, which is slightly soluble solid, cannot be dissolved in a herbicidally active ingredient of thiolcarbamate type, the slightly soluble solids are precipitated after formulation, whereby the desired storage stability cannot be obtained.
As a conventional art to dissolve an agricultural chemical ingredient in a hydrophobic solvent and to suspend another agricultural chemical ingredient which is slightly soluble therein, there is a complex agricultural chemical composition (Japanese Patent Application First Publication No. 57-2202). The complex composition includes an organic solvent, whereby it has above-mentioned problems due to an organic solvent. In addition, little amount of the slightly soluble agricultural chemical ingredient included in the complex composition causes drawbacks such that a stabilized suspension cannot be obtained and the desired storage stability may not be obtained.
As a conventional art to disperse and suspend a herbicidally active solid ingredient, which is slightly soluble, in a solution of water-soluble herbicidally active ingredient in the presence of a surfactant, a water suspension type of a complex herbicide (Japanese Patent Application Second Publication No. 63-37761) is known. However, it is impossible to formulate a herbicidally active ingredient of thiolcarbamate type by using this art because the herbicidally active thiolcarbamate ingredient is slightly soluble in water.
As a conventional art to disperse uniformly in water or an organic solvent, which is slightly soluble in water, an organic solvent, or a liquid agricultural chemical, an agricultural chemical, in order to improve a storage stability thereof, there is a suspensibility agricultural chemical dissemination agent (Japanese Patent Application Second Publication No. 54-11368). It is possible to formulate a herbicidally active ingredient of thiolcarbamate type by mixing fine powders of colloidal aluminum silicate hydrate and an organic solvent such as a glycol solvent and the like in accordance with the embodiments described in the Japanese patent application. This art has a drawback such as using an organic solvent therein, and therefore, does not contribute to resolving the problems of an organic solvent.
Therefore, in order to obtain a complex herbicide formulation, which includes a herbicidally active thiolcarbamate ingredient useful for controlling agriculturally hazardous gramineous weeds so as to have a wide spectrum for controlling weeds, it is strongly desired to develop an agricultural chemical formulation comprising a herbicidally active ingredient of thiolcarbamate type and another solid herbicidally active ingredient, which is slightly soluble in the herbicidally active thiolcarbamate ingredient, wherein said another solid herbicidally active ingredient is suspended and dispersed in said herbicidally active ingredient of thiolcarbamate type, so as to be diluted and applied without the above-mentioned problems with respect to an organic solvent and a surfactant.